* Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > Here I resend it: > > > From: Mikulas Patocka <mpatocka@xxxxxxxxxx> > Subject: [PATCH] x86: optimize memcpy_flushcache > > I use memcpy_flushcache in my persistent memory driver for metadata > updates, there are many 8-byte and 16-byte updates and it turns out that > the overhead of memcpy_flushcache causes 2% performance degradation > compared to "movnti" instruction explicitly coded using inline assembler. > > The tests were done on a Skylake processor with persistent memory emulated > using the "memmap" kernel parameter. dd was used to copy data to the > dm-writecache target. > > This patch recognizes memcpy_flushcache calls with constant short length > and turns them into inline assembler - so that I don't have to use inline > assembler in the driver. > > Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > > --- > arch/x86/include/asm/string_64.h | 20 +++++++++++++++++++- > arch/x86/lib/usercopy_64.c | 4 ++-- > 2 files changed, 21 insertions(+), 3 deletions(-) Applied to tip:x86/asm, thanks! I'll push it out later today after some testing. Thanks, Ingo -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
